The advent of optical disc storage has given rise to many optical disc storage formats. One such format is the audio optical disc, which is commonly referred to as the "Compact Disc" (or "CD"). Another format is the computer data optical disc, which is commonly referred to as the "Compact Disc Read Only Memory" (or "CD-ROM"). However, regardless of the storage format used, optical discs are generally similar in their physical layout. That is, in a typical optical disc information is recorded by forming "pits" in the disc, the pits being circumferentially arranged to form a multiple of concentric "tracks", and the tracks lying within an "optical layer" (or plane of focus).
To read information stored on an optical disc, the disc is rotated while a beam of light is directed at the disc, and the reflections of the beam by the disc are monitored--the arrangement of pits on the disc being determinable from the monitored reflections and the stored information being determinable from the arrangement of pits. However, before attempting to read information from the disc, the reading system must be calibrated, or "initialized". That is, the value of certain system parameters must be initially determined so that the, light beam can be properly focused on the optical layer and can properly follow the pitted tracks within the layer. Since the typical disc has only one optical layer, the initialization procedure is performed only once when reading a typical disc.
The same initialization procedure that is used for the typical disc may be used for certain non-typical discs. For example, the above-described initialization procedure is sufficient for use in a two-sided/one-optical-layer-per-side system. In such a system a disc has two readable sides with each side having one optical layer, and therefore the standard initialization procedure is simply applied to each side in the same manner that it is applied in the one sided (typical) disc. However, the standard initialization procedure is not adequate for all non-typical discs, such as the multilayer disc, in which one or both sides of the disc has multiple optical layers.